A field-device electronics for a field device. The field device electronics is supplied from an external electrical energy supply providing a supply voltage and delivering a variable supply current driven by the supply voltage. The field-device electronics includes an internal control unit for controlling the field device, as well as at least one internal supply circuit feeding the internal control unit. The supply current is a mixed current formed by superimposing and/or modulation of an alternating current portion onto a direct current portion. The internal supply circuit uses, at least at times and/or at least in part, also the alternating current portion of the mixed current for covering an instantaneous energy requirement of the control unit.